Problems installing qt3-dev via apt/synaptic

[Bill Preder]

Hi,

After about two years of diddling around with different distributions on my
Titanium PowerBook, I'm finding Ubuntu to be the most gratifying and painless
one I've yet come across.  Most notably, I'm having the greatest success with
sound apps to date.  In trying to get my Linux PPC sound machine rockin',
though, I've hit one snag:

A number of apps I've tried to install or compile (not all from
apt-get/synaptic) depend on the development version of qt3.  When I try to
install libqt3-dev through synaptic, I get an unresovable dependency error,
stating a dependency on libpng12-0-dev.  Unfortunately, synaptic won't let me
install libpng12-0-dev because the runtime version was already installed
(labeled as version "1.2.5.0-7ubuntu1") as part of the default Ubuntu
installation (?).  Instead, I get the error 

libpng12-dev:
  Depends: libpng12-0 but 1.2.5.0-7ubuntu1 is to be installed

(...which makes me scratch my head because libpng12-0 *is* already installed,
but with the 1.2.5.0-7ubuntu1 version label...)

So it seems the only way to get the dev version installed is to remove the
runtime version.  Unfortunately, if I use apt/synaptic, that also means trashing
a HUGE amount of software already installed -- if I have to do this, it seems
like I'd just about have to start all over from scratch.

Needless to say, I'd really like to avoid this.  Is there a relatively safe way
I can force the dev version of libpng on top of the runtime?

Thanks,
Bill